Engine Variations

The early versions were treacherous.

Pressurized frames were not exclusive to 917s among Porsches.

 

The 917s were dangerous safety wise, I think one of the Rodreiuqos brothers was killed in one. I saw both crank configurations in the back room of a museum that had spare parts for the 917s it had in its collection. I don't know what and when, or if both crank configurations actually raced. The 16 cyl.engine, I just read about it. It just shows how serious Porsche was about winning. The Porsche turbo 12 cyl. car that Mark Donahue drove in Can Am, finished the series. There was nothing even remotely competitive with it.

 

What museum was that? Could it be possible that the parts you saw were for a preliminary test lashup motor made of back-to-back 911 engines (which had the boxer configuration), but that they decided on the paired crank throws for the real thing to make the engine more compact?

Porsche would go to some great lengths of development in the day, but was also quite frugal - for example, they had to show first 50, then later 25 (after appeal) completed 917s to homologate them for Lemans prototypes. Most of the 25 were later broken down for spare parts and were only built to document having 25 for the officials.

The source I have on the development of this car is "The Making of a Winner - the Porsche 917" by Larry Pihera.

Sadly - you are right - That super-turbo 917-30 finished not only Can-Am, but Mark Donohue as well. It is still thought to be the most powerful racing car ever to run in a competitive road or track series - only a fuel dragster could out HP it.

 

I should have reworded the term museum, It was a private collection of that had multiple 917s and other significant racing cars. You could be correct on mockup engines because I just saw the loose crankshafts on the parts shelves. When they obtained the cars the parts probably came with the lot.


Ago

 

Thanks, AGO - that does begin to make sense. I sent you a PM back.

 

BTW - for RifleDriver and others who think that the Testarossa is a 180 degree V-12 instead of a flat 12 -

Should we also say that a BMW inline six is a 0 degree V-6?

 

A three hundred sixty degree V6 sounds better.

 

Touche'

Can't agree with your terminology here -- a 180 deg V12 and a 12 cyl (true) Boxer engines are both flat 12s IMO (but a 180 deg V12 is not a 12 cyl Boxer engine).

 

My terminology (like my mind) is childishly simple:

Inline engines have all cylinders inline.

V engines have two banks in the shape of a V. Flat things are not V things in plain English.

Flat engines have two banks which are opposed at 180 degrees.

The configuration of the crankshaft (paired rods or separate) has nothing to do with the above.

 

As for the flat V12 in the Testarossa, here is why it is called that.

I was corrected on this a couple of years ago, as I was under the false impresion that the Testarossa had a flat crank (180°) which it does not.

The block of the engine is flat, with the cylinders 180° apart. However the crank in not flat, the crank is actually 160°, making it an extremely wide V. That is why it the Testarossa enigne is a flat V12.

Flat block/V crank.

Capiche?

 

Throws spaced at 120°

 

Alrighty then.

 

As I remember Ferrari chose that configuration because they could use some of tooling they already had for the 60 deg V12s.

 

Flat is flat. Vee is Vee. Inline is Inline.

It really is not all that complicated.

 

Advantages to a flat 12 (A.K.A horizontally opposed): lower engine 'boxing' movements makes mountnig the engine easier.

Advantages to a flat V12: easier to machine the crank shaft.

As to aero: a 120 degree V12 would have a lower center of gravity (than a 60 degree V12) and better underbody aero than a flat 12.

 

I was at the Porsche museum about a year ago. They had on display the cut away 917 engine. They also had a 917 titanium crank, it had the shared throw configuration.